Cutting tool with detachably connected inserts

ABSTRACT

The invention relates to a cutting tool, for example, a saw blade ( 1 ) with a base body ( 2 ) that has at least one bit seat in which an insert ( 7 ) is held. It is provided according to the invention that the base body ( 2 ) has at least one elastically deformable clamping element ( 3 ) that can be placed against the insert ( 7 ) with the aid of a control element ( 5 ) positioned in a recess of the base body ( 2 ) in order to hold the insert in the bit seat.

The invention relates to a cutting tool with a base body that has atleast one bit seat in which an insert is held.

With cutting tools of this type, it should be possible on the one handto fix inserts in the bit seat as firmly as possible in order to avoid adetachment of inserts during use. On the other hand, particularly withcutting tools that have a plurality of bit seats and accordingly areequipped with many inserts, a detachable fixing of the inserts isdesirable so that individual inserts can be replaced as soon as they areworn.

Inserts can be attached to the base body of a cutting tool in variousways as a rule, as shown below for saw blades by way of example.

For example, in the case of saw blades that are embodied with bit seatsdistributed on the circumference of a base body, in which bit seatsinserts are held, which cause a chip removal on the processed workpieceupon rotation of the saw blade, the individual inserts are attached tothe base body by soldering. However, this has the disadvantage that onlya single cutting geometry can be used. Namely as soon as the inserts areconnected by soldering to the base body, a cutting geometry can nolonger be changed. Furthermore, the disadvantage is also associated withsoldering that a resharpening must always be carried out on-site. Adetachment of individual inserts and an individual, professionalresharpening by the insert manufacturer are not possible. The entire sawblade must also be replaced when only a part of the inserts has becomeunusable.

Another method is to attach the individual inserts to the base body byscrews. Apart from the fact that a fastening hole has to be provided forthis purpose in each insert, which impairs a stability of the insert inthe bit seat, this method can be used only for inserts that have acertain minimum size. In the case of small inserts, such as are used forsmall cutting widths, a screw fastening is not possible.

Another method is to clamp the individual inserts into yielding,V-shaped bit seats of the base body (so-called self-grip systems). Inthis case a particularly precise manufacture of the bit seats isnecessary with extremely low tolerances. This entails a high laborexpenditure in the production of the base body. In addition, a furtherdisadvantage is given in that an undesirable detachment of the insertsor cutting teeth may occur with extreme loads.

A similar method to that described above is to place inserts into aV-shaped bit seat of a base body and to fix them there with wedge-shapedpins. However, a particularly exact production of the bit seats is alsonecessary in this case. Furthermore, the inserts must be provided withrecesses for the pins, which weakens the inserts.

Starting from this prior art, the object of the invention is to disclosea cutting tool of the type mentioned at the outset to which one or moreinserts can be detachably fixed in a simple manner and with high force.

This object is attained with a cutting tool of the type mentioned at theoutset in that the base body has at least one elastically deformableclamping element that can be placed against the insert with the aid of acontrol element positioned in a recess of the base body in order to holdthe insert in the bit seat.

The advantages achieved with a cutting tool according to the inventionare to be seen in particular in that the inserts provided can bedetachably fixed to the base body in a simple manner with extremely highforce. It is therefore now also possible, for example, to detachablymount inserts in the case of saw blades with a diameter of more than 2.5meters without having to fear a detachment of individual inserts fromthe bit seats during cutting or sawing. At the same time it renderspossible the combination provided according to the invention of clampingelements with control elements that are respectively shaped orpositioned in the base body to realize even very small cutting widths.For example, saw blades of any desired thinness can be used since theelements provided for the attachment of an insert can be providedregardless of a thickness of the saw blade.

Another important advantage of a cutting tool according to the inventionlies in that, compared to other known solutions, in particular self-gripsystems, the bit seats can be produced with relatively large tolerances.Namely, while with self-grip systems the bit seats must be producedexactly to a hundredth of a millimeter so that an insert can be fixed byclamping, substantially greater tolerances can be provided with acutting tool according to the invention, like a saw blade, becauseinaccuracies of production can be easily surmounted with the applicationof the clamping elements. A much lower preparation or productionexpenditure for the base body is therefore given.

The attachment system provided according to the invention has provenvaluable in particular when several bit seats are provided in whichrespectively one insert is held by means of respectively one clampingelement and a control element interacting therewith. Individual insertscan then easily be replaced in the case of cutting tools with aplurality of inserts.

The at least one clamping element is preferably embodied as an integralpart of the base body or represents an elastically deformable areathereof.

With respect to a simple production as well as a high stability of thecutting tool in use, it is preferred that the base body is embodied as awhole in one part. Expediently the base body is thereby made of steel,in particular a steel with high toughness.

The elastically deformable clamping element(s) provided can be shaped inthe base body in different ways, for example, through water-jet cuttingor wire spark eroding. It has proven valuable to cut the clampingelements into the base body by means of a laser. The bit seats can alsobe cut into the base body thereby at the same time.

The shaped clamping element(s) can be embodied such that they have anose that can be placed against an insert, to which nose an arm connectsat an angle and is preferably embodied tapering towards the center ofthe base body.

The clamping elements can thereby be placed against the inserts withrelatively low force by activation of the control elements. It ispreferred thereby that the at least one clamping element is connected tothe control element at the transition from the nose to the arm. Uponactivation or fixing of an insert, the control element then presses on anose, through which the clamping element is deformed at its weakestpoint, namely at the end of the arm opposite the transition. A forcenecessary for fixing the insert is minimized due to the taperedembodiment of the opposite end and a lever effect.

The control element(s) provided in recesses of the base body can berealized in various ways. For this any elements can be used that permita clamping element to be pressed onto an insert upon activation. In avery simple embodiment a control element of this type can comprise onlya screw. With respect to a particularly effective attachment, however,it is preferred for the control element to comprise a partiallyapproximately circular, rotatable body that bears in two edge areas ofthe recess and against the clamping element. A 3-point contact or a3-point seat is thus created for the rotatable body, due to which thebody is held in the recess safe from tipping regardless of its position.At the same time a contact surface between the body and other parts ofthe cutting tool is small, which is why the body can be rotated with lowforce if required. For example, it is possible that the rotatable bodycomprises a cam bearing against the clamping element so that the atleast one clamping element can be brought from an open position into aposition fixing the insert and vice versa by rotating the body. Thisembodiment has the advantages with respect to saw blades that, on theone hand, each control element to be activated is easily accessible atthe side of the saw blade and that, on the other hand, the controlelement is virtually wedged through the cam provided between theclamping element and areas of the recess of the base body in which itsits, which leads to a particularly firm locking when the insert isfixed. Alternatively, it is also possible for the rotatable body tocomprise an indentation bearing against the clamping element, whichindentation bears against a protrusion of the clamping element so thatthe at least one clamping element can be brought from an open positioninto a position fixing the insert and vice versa by rotating the body.

With respect to the firmest possible fixing of the insert, it canfurthermore be provided that a bit seat or an insert is arrangedapproximately perpendicular to a rotational direction of the cuttingtool and the at least one clamping element can be placed against theinsert in the opposite direction to the rotational direction. Highforces occurring during cutting can thus be effectively counteracted.

For highest cutting capacities and cutting tools with large dimensions,for example, saw blades with a diameter of up to four meters, it can beadvisable for bit seats to be embodied with projections preferablyrunning in the radial direction of the base body and for the inserts tohave corresponding indentations in their base areas. Axial forcesoccurring during cutting can thus be counteracted.

A suitable insert can be provided for a cutting tool according to theinvention such as a saw blade if the insert on its top surface has anactive cutting area with the cutting edge at one end and an attachmentarea at an opposite end, a rib being provided between the active cuttingarea and the attachment, which rib is raised with respect to theadjacent areas of the active cutting area and the attachment area.Through the provided embodiment with a raised rib between the activecutting area and the attachment area, on the one hand, a separation ofthe cited areas is achieved so that the attachment area is protectedduring cutting from hot chips being discharged. On the other hand, aclamping element of the base body can come to rest on the rib, whereby aretention of the insert in a bit seat is improved.

The insert is preferably embodied such that a chip trough adjoins thecutting edge and merges into the rib. If this measure is provided, chipsremoved can be guided away in an advantageous manner.

In order to achieve a good fixing of the insert in a bit seat by meansof a clamping element, it is recommended that the attachment area has afirst zone adjoining the rib and rising in cross section and a secondzone adjoining the first zone and sloping downward in cross section.This prevents an insert from moving in the radial direction duringcutting or with acting cutting forces.

In order that a good positive closure can be achieved with a clampingelement, it can furthermore be provided that troughs are formed in thefirst and/or second zone. The troughs thereby preferably runsymmetrically to a longitudinal axis of the insert.

An insert used according to the invention can furthermore be embodied inplan view in an elongated manner and with an active cutting area that iswidened compared to the attachment area.

The rib provided preferably runs perpendicular to the longitudinal axisof the insert so that a separation from the attachment area and activecutting area is given over the entire width of the insert.

It can furthermore be provided that the insert has one or moreindentations in the region of its base area, which indentationspreferably run over an entire length and/or width of the base area. Thismakes it possible to achieve a positive closure in the region of thebase area of the insert in interaction with a bit seat havingcorresponding projections, when the insert is attached to the saw blade.

Further features, advantages and effects of the invention are shown bythe context of the specification and the following exemplaryembodiments, based on which the invention is shown in still more detail.The drawings show:

FIG. 1 A partial area of a saw blade according to the invention with aclamping element in opened position;

FIG. 2 A section along the line II-II in FIG. 1;

FIG. 3 A section along the line III-III in FIG. 1;

FIG. 4 A partial area of a saw blade according to the invention with aclamping element in fixing position;

FIG. 5 A section along the line V-V in FIG. 4;

FIG. 6 A section along the line VI-VI in FIG. 4;

FIG. 7 A side view of an insert;

FIG. 8 A rear view of an insert;

FIG. 9 A front view of an insert;

FIG. 10 An insert in plan view;

FIG. 11 A partial area of a saw blade according to the invention with aclamping element in opened position;

FIG. 12 A partial area of a saw blade according to the invention with aclamping element in fixing position.

FIG. 1 shows in more detail a partial area of a cutting tool accordingto the invention in the form of a saw blade 1. The approximatelycircular saw blade 1 comprises a base body 2 that is formed from anessentially planar circular flat material. A very tough steel ispreferably used as the flat material, in which a bit seat with two areas61, 62 as well as a gap 64 is cut by means of laser. The gap 64 isprovided so that the areas 61, 62 can be reworked by grinding.

Furthermore, the base body 2 has a shaped clamping element 3, which likethe bit seat is cut into the base body 2 by means of a laser. Theclamping element 3, seen from the center of the base body 2, has an arm32, first embodied in a tapering manner and then widening approximatelyin the radial direction, on which arm a nose 31 is shaped at an angle ofapprox. 80° to 135°. In the area of its end directed to the center ofthe base body 2, the arm 32 is surrounded by two free spaces 33, 34,which together with the tapered embodiment at the one end ensure a goodelastic deformability of the arm 32 in this area. Another free space 35is provided beneath the arm 32 in order to make it possible to place theclamping element 3 against an insert 7, which bears against the areas61, 62 in a bit seat and the projecting cutting edge 73 of whichdescribes an outer orbit of the saw blade 1. In order to render possiblethis placement of the clamping element 3 in a simple manner, a controlelement 5 embodied in part in an approximately circular manner in planview with a cam 51 is held in a rotatable manner in a recess of the basebody 2 likewise cut by means of a laser. On the one hand, the controlelement 5 in the approximately circular area bears against anon-deformable zone of the base body 2 at two points and, on the otherhand, as can be seen from FIG. 1 and the detailed view provided in thisfigure, against the clamping element 3 in the region of a transitionfrom the nose 31 to the arm 32.

With the situation shown in FIG. 1, the cam 51 of the control element 5is in a position in which the clamping element 3 is not depressed, butis opened and the insert 7 can be removed from the bit seat or insertedtherein. This can be necessary, for example, when an individual insert 7of a saw blade 1 must be replaced, for example, because it needs to beground or is worn and must be replaced. In this situation a ground endarea 36 of the nose 31 is spaced approx. 1 to 2 millimeters apart fromthe surface or top area 73 of the insert 7. If the eccentric or thecontrol means 5 is now turned counter-clockwise, a pressure is exertedthrough the cam 51 onto the clamping element 3 so that due to itsflexibility it moves towards the insert 7 and fixes the insertultimately with its force acting against a rotational direction R of thesaw blade 1 (FIG. 4). The control element 5 with the cam 51 is therebytransferred into a locking position that causes a firm fixing of theinsert 7. The control means 5 can expediently be equipped with seats fora torque wrench so that a locking or fixing of the insert 7, as shown inFIG. 4, can take place with particularly low expenditure of force. Inorder to achieve the desired locking with the lowest possibleexpenditure of force and to render possible a continuously variableadjustment of a bearing pressure, in addition, as shown in FIGS. 1 and4, an area of the clamping element 3 in contact with the cam 51 can beembodied in a concave manner.

As can be seen based on the sectional views, not to scale, of FIGS. 2,3, 5 and 6, a bit seat with a projection 63 is provided, which extendsin the radial direction of the base body 2 over the entire length of thebit seat. The insert 7 has a corresponding indentation 711 so that notonly a non-positive engagement but also a positive engagement isachieved in the region of a base area 71 of the insert 7. Similarly, theclamping element 3 has ground projections in an end area 36 of the nose31, which projections correspond in their geometry to correspondingtroughs in the top surface 72 of the insert 7, into which troughs theyengage. Overall a highly effective non-positive engagement and positiveengagement can be achieved thereby, so that high radial forces as wellas axial forces can be controlled during cutting.

An insert 7 used according to the invention is shown in more detail inFIGS. 7 through 10. As can be seen from FIG. 7, the insert 7 has a basesurface 71 and a top surface area 72 lying opposite, which are connectedto one another via side surfaces 74. In the area of the top surface 72,the inset 7 at one end has a cutting edge 73 that provides a chipremoval during use. The cutting edge 73 is adjoined by a chip trough 78embodied in a deepened manner, on which removed chips glide off. Thischip trough 78 merges directly into a rib 77 that is dimensioned in itsshape and height such that it can form a virtually continuous surfacewith a back 311 of a nose 31 of a clamping element 3, which provides theadvantage that chips removed can flow off in an optimal manner. This canbe important in particular when a formation of long chips is given dueto the cutting conditions and/or the materials processed.

An attachment area with two zones 761, 762 is provided at the end of theinsert 7 opposite the cutting edge 73, wherein a first zone 761 directlyadjoins or merges into the rib 77. As can be seen in particular fromFIG. 7 and FIG. 10, which shows an insert 7 pursuant to FIG. 7 seen indirection X, the zones 761, 762 are embodied with troughs that runsymmetrically to a longitudinal axis Y of the insert 7. Correspondingprojections of a clamping element 3 can engage in these troughs so thatthe insert 7 is secured against an axial displacement or slipping. Inorder to prevent a displacement of the insert 7 in the radial directionat the same time, it is provided that in cross section the first zone761 is embodied in a rising manner and the second zone 762 in adownwardly sloping manner. Furthermore, an indentation 711 can beprovided in the area of the base surface 71 running along thelongitudinal axis Y so that in a similar manner a positive closure canbe achieved in the area of the base surface 71.

Due to the provided embodiment of the insert 7, the insert 7 can befixed to a saw blade 1 according to the invention in a non-positive andpositive manner. As can be seen from FIG. 10, this makes it possible toembody the active cutting area 75 in a wider manner than the attachmentarea 76, which provides the advantage that the saw blade 1 is alwaysfree-running during cutting.

In FIGS. 11 and 12 partial areas of another variant of a saw blade 1 areshown in side view, wherein the partial areas comprise a single insert7. The insert 7 sits loosely in the bit seat in the situation shown inFIG. 11. The control element 5, which is embodied as a rotatable body,has an indentation 52, as can be seen in particular from the detail viewin FIG. 11. This indentation 52 interacts with a protrusion 37 of theclamping element 3 and is adapted in its shape approximately thereto.The rotatable body or the control element 5 is therefore in contact withthe clamping element 3 in the area of the indentation 52. Furthermore,the control element 5 bears only in two separate areas against the endof the recess in which it is located. A 3-point contact or a 3-pointseat is thus created for the rotatable body. This 3-point seat, in whichthe centers of the individual contact areas, as in the embodimentvariant previously shown, are arranged approximately at an angle ofrespectively 120°, leads to a high stability of the rotatable body whenthe insert 7 is fixed, which is shown in FIG. 12. The 3-point seat alsohas advantages during the fixing itself or during detachment, since onthe one hand a resistance during activation of the clamping element 3 orrotation of the body is low, and on the other hand the rotatable bodydoes not tend to jam, which could definitely be given with a full-areaseat and strong torsion of a saw blade during cutting.

Compared to the variant shown in FIGS. 1 through 4, additionaladvantages are evident in this embodiment with respect to the stabilityof the position of the rotatable body and the fixing of an insert 7during cutting so that this variant is used in particular forapplications with particularly demanding load profiles.

1. Cutting tool with a base body (2) that has at least one bit seat inwhich an insert (7) is held, characterized in that the base body (2) hasat least one elastically deformable clamping element (3) that can beplaced against the insert (7) with the aid of a control element (5)positioned in a recess of the base body (2) in order to hold the insertin the bit seat.
 2. Cutting tool according to claim 1, characterized inthat several bit seats are provided in which respectively one insert (7)is held by means of respectively one clamping element (3) and a controlelement (5) interacting therewith.
 3. Cutting tool according to claim 1,characterized in that the at least one clamping element (3) is embodiedas an integral part of the base body (2).
 4. Cutting tool according toclaim 1, characterized in that the base body (2) is embodied as a wholein one piece.
 5. Cutting tool according to claim 4, characterized inthat the base body (2) is made of a steel.
 6. Cutting tool according toclaim 5, characterized in that the at least one clamping element (3) iscut into the base body (2) by means of a laser.
 7. Cutting toolaccording to claim 1, characterized in that the at least one clampingelement (3) has a nose (31) that can be placed against the insert (7),to which an arm (32) adjoins preferably at an angle.
 8. Cutting toolaccording to claim 7, characterized in that the arm (32) is embodiedtapering towards the interior or center of the base body (2).
 9. Cuttingtool according to claim 8, characterized in that the at least oneclamping element (3) is connected to the control element (5) at thetransition from the nose (31) to the arm (32).
 10. Cutting toolaccording to claim 1, characterized in that the control element (5)comprises a partially approximately circular, rotatable body that bearsin two edge areas of the recess and against the clamping element (3).11. Cutting tool according to claim 10, characterized in that therotatable body comprises a cam (51) bearing against the clamping element(3), so that the at least one clamping element (3) can be brought froman open position into a position fixing the insert (7) and vice versa byrotating the body.
 12. Cutting tool according to claim 10, characterizedin that the rotatable body comprises an indentation (52) that bearsagainst a protrusion (37) of the clamping element (3) so that the atleast one clamping element (3) can be brought from an open position intoa position fixing the insert (7) and vice versa by rotating the body.13. Cutting tool according to claim 1, characterized in that the bitseat or the insert (7) is arranged approximately perpendicular to arotational direction (R) of the cutting tool and the at least onceclamping element (3) can be placed against the insert (7) in theopposite direction to the rotational direction (R).
 14. Cutting toolaccording to claim 1, characterized in that the at least one bit seat isembodied with projections (63) running preferably in the radialdirection of the base body (2) and the insert (7) has correspondingindentations (711) in its base surface (71).
 15. Cutting tool accordingto claim 1, characterized in that the cutting tool is a saw blade (1).